Abstract
Unreinforced masonry buildings undergoing seismic actions often exhibit local failure mechanisms which represent a serious life-safety hazard, as recent strong earthquakes have shown. Compared to new buildings, older unreinforced masonry buildings are more vulnerable, not only because they have been designed without or with limited seismic loading requirements, but also because horizontal structures and connections amid the walls are not always effective. Also, Out-Of-Plane (OOP) mechanisms can be caused by significant slenderness of the walls even if connections are effective. The purpose of this paper is to derive typological fragility functions for unreinforced masonry walls considering OOP local failure mechanisms. In the case of slender walls with good material properties, the OOP response can be modeled with reference to an assembly of rigid bodies undergoing rocking motion. In particular, depending on its configuration, a wall is assumed either as a single rigid body undergoing simple one-sided rocking or a system of two coupled rigid bodies rocking along their common edge. A set of 44 ground motions from earthquake events occurred from 1972 to 2017 in Italy is used in this study. The likelihood of collapse is calculated via Multiple Stripe Analysis (MSA) from a given wall undergoing a specific ground motion. Then, the single fragility functions are suitably combined to define a typological fragility function for a class of buildings. The procedure is applied to a historical aggregate in the city center of Ferrara (Italy) as a case study. The fragility functions developed in this research can be a helpful tool for assessing seismic damage and economic losses in unreinforced masonry buildings on a regional scale.
Highlights
UnReinforced Masonry (URM) buildings represent a large part of the Italian building stock
In Italian historical centers, this is essentially due to the following causes: (i) Old buildings may have been strongly altered over time, often resulting in a reduction of cross-section areas of masonry walls, a general weakening of mutual connections between walls and floors, and sometimes a significant increase in the seismic masses
Aleatory uncertainty is classified as irreducible uncertainty and refers to a property of the system associated with variability, whereas epistemic uncertainty can be reduced and it is associated with a lack of knowledge by the analyst (Beer et al 2013)
Summary
UnReinforced Masonry (URM) buildings represent a large part of the Italian building stock. Under seismic actions, existing URM buildings are often subjected to local collapse mechanisms involving partial or whole OOP failure of façade walls (D’Ayala and Speranza 2003; D’Ayala 2005, 2013; Maio et al 2016). Both activation and evolution up to collapse of these mechanisms strictly depend on stiffness and strength of connections between facade walls and other structural elements such as partition walls, floors and roof
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.